From the workshop, to the garden, to the kitchen, motor-driven portable electric power tools and appliances have provided society with the ability to perform large tasks at a relatively quicker pace than manual counterparts. Whether the tool is a hedge trimmer, a sander, or a kitchen carving knife, an operator may often require that the tool be maintained in an activated or On state for extended periods of time in order to accomplish a desired task.
As those skilled in the art recognize, on such occasions, the operator must keep the activation switch of the tool continuously actuated. This continuous actuation is typically achieved through force or pressure exerted by the operator's hand or fingers, eventually causing the operator to experience general fatigue and sore appendages. Therefore, various control mechanisms for portable power tools have been designed which incorporate a latching mechanism to allow the operator to lock the tool in an activated or On state.
It is also recognized in the art that, if handled in a certain manner, a portable electric power tool could become inadvertently engaged. Therefore, control mechanisms have been designed with these tools in mind which mandate the simultaneous actuation of two or more trigger devices in order to energize the motor of the tool. Thus, the likelihood of inadvertent activation of a tool is minimized by requiring the operator to perform a sequence of steps before the motor for operating the tool may become engaged.
Current control devices for portable power tools exist which require simultaneous actuation of components to activate the tool, as well as provide a feature to keep the tool activated in a locked on state. One such arrangement features a one-piece mechanism having two ends which each require activation in order to actuate the switch. Other prior art arrangements include U.S. Pat. No. 4,271,342 issued to Sistare; U.S. Pat. No. 4,291,207 issued to Reinke et al; U.S. Pat. No. 4,449,062 issued to Wilson; U.S. Pat. No. 4,820,889 issued to Seghetti; U.S. Pat. No. 4,879,438 issued to Winchester; U.S. Pat. No. 4,934,494 issued to Fushiya et al; and U.S. Pat. No. 5,150,523 issued to McCurry.
Consequently, a need has developed for an improved trigger mechanism which is capable of being locked in a Locked-on state so that the operator may operate the tool for extended periods of time without experiencing fatigue or accompanying soreness. In addition, the operator should be able to quickly and easily release the trigger mechanism from the Locked-on state.
Further, a need has developed for an improved trigger mechanism for a portable electric power tool which minimizes unwanted activation of the tool by requiring the simultaneous actuation of two separate elements of the mechanism in order to energize the motor of the tool.